(a) Field of the Invention
The present invention relates to improvements in fountain designs, more particularly fountain pan designs of the type used for dampening rolls, and possibly other type rolls, of printing presses. It also relates to a method of maintaining a uniform temperature of the liquid in such fountains as measured along the length of the dampening roll, during operation of the press. It still further relates to a method of cleaning a fountain solution of a printing press.
(b) Description of Prior Art
The prior art fountain designs used for dampening rolls commonly comprise an elongated fountain pan wherein liquid, usually refrigerated dampening solution, sometimes containing alcohol, is introduced into one end thereof and is discharged adjacent the opposite end thereof. During operation of the press, the dampening rolls become heated, which in turn transfer heat to the pan liquid. Due to the position of the liquid inlet and outlet in the pan, the heated roll is subjected to non-uniform cooling along its length by the entering cooled liquid. As the cooled liquid moves along the pan toward the outlet it is heated, thus providing a differential in liquid temperature along the length of the pan and accordingly across the width of the dampening roll. As a result, the quality of printing by the press is affected.
Although some attempts have been made in the past to improve distribution of fluid entering the fountain pans, the aforementioned temperature differential problem remains.
Another drawback in respect of the prior art fountain designs is their lack of an efficient preliminary cleaning-filtering of the liquid being returned to the cleaning reservoir. The preliminary cleaning method of the prior art devices commonly comprises use of a single stand pipe (adjustable in height) in the pan. Such a device provides a limited overflow surface, accordingly a limited flow capacity, affecting volume of return flow to the reservoir. Furthermore, regarding the prior art devices, a relatively long path exists over which the liquid must travel from its point of entry into the pan to its point of departure from the pan, resulting in a number of disadvantages, including delay in dumping the heated liquid and delay in ridding the liquid of its foreign matter.
A further drawback in respect of the prior art designs is their lack of an efficient mechanism to permit proper throttling of the liquid entering the fountain pen. The integral throttling mechanism according to the present invention overcomes this drawback.
A further drawback in respect of the prior art devices is they do not permit continued running of the press while servicing the dampening roll fountain.
A further drawback in respect of the prior art devices is the need to insulate the fountain pan.